Hi Thiago,

>> I agree that we should first merge the GSOC code from this year before
>> we start thinking of a new segmenter. Let me know if you need any
>> help. However, I think both a graph-cut-based segmenter and SIOX could
>> have a place in GIMP side-by-side. Graphcut-based segmenters and SIOX
>> have different complementary properties. It is going to be a GUI
>> challenge though because it requires expert knowledge to know when to
>>  use which.
> I do believe that using both algorithms could be a nice solution. In fact,
> it was my original proposal and I am willing to try to merge both methods.

Except the main issue is that it would require expert knowledge to know
which one to use. I think the challenge is to provide the user with a nice way
of switching between the two. This will become even more complicated once the
detail refinement brush is implemented in the main branch to deal with
border inaccuracies.

>> Thiago: I can give you a couple of pictures that you should try with
>> your segmenter and then compare against SIOX... especially those with
>> a lot of texture and semi-transparent layers. The new version of SIOX
>> can cope with them very well. Graph-based segmentation algorithms
>> can't because they look for a minimum cut, which is a problem because
>> especially those highly complicated pictures require a lot of time to
>>  do manually.
> I would be very glad if you could provide me some of these examples, because
> it would really help me with my research. Also, I would like to state that
> our approach is *not* based on the min-cut/max-flow algorithm, so it does
> not suffer with many of its drawbacks. Right now my current job is to deal
> with soft segmentation in an attempt to cope with the transparency issue,
> and we already have some good solutions.

First: Try any image that works well and add 80% noise. SIOX is pretty
good with noise.
Last time I tried Grabcut with such an image, I got a segmentation fault...

Then: Try images like this one:
and try to extract the tree. The current GIMP version in the main branch
cannot do it, the version from last Google Summer of Code can do it.
Graph-based algorithms usually have problems but I think this is an
important feature
because it saves HOURS of work to be able to do it semi-automatically!


Dr. Gerald Friedland
International Computer Science Institute
1947 Center Street, Suite 600
CA-94704 Berkeley, USA
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